Speaking with a KN95 face mask: a within-subjects study on speaker adaptation and strategies to improve intelligibility

Cognitive Research: Principles and Implications

Table 1 Stimuli and measures for each protocol and condition

Protocol	Conditions	Stimulus	Outcome measure
KN95 mask acoustic profile	Mannequin: “No Mask” “Mask”	Computer-generated white noise	Signal attenuation (Mask minus No Mask)
KN95 mask acoustic profile	Mannequin: “No Mask” “Mask”	Computer-generated white noise	1/3 octave band analysis
Human	Human: “No Mask” “Mask Only”	Sustained /a/	Phonatory measures (LHR, duration, F0, shimmer, jitter, HNR)
	Human: “No Mask” “Mask Only” “Clear + Mask” “Loud + Mask” “Slow + Mask”	VAS survey	Speaker effort
		SIT	Transcription intelligibility
		Story read task	Formant measures (F1 and F2 range)
		Spoken paragraph	Kinematic measures (Jaw ROM and speed; Head ROM and Speed)
Phonatory compensation to KN95 mask	Human + mannequin: “Masked Human” (maskless mannequin) “Masked Mannequin” (maskless human)	Human-produced sustained /a/ from “No Mask” and “Mask Only” conditions	Phonatory measures (LHR, duration, F0, shimmer, jitter, HNR)